This invention is directed to a rotary spray arm means as a part of dishwashers and particularly those having upper and lower racks and separate spray arms associated with each rack. In the dishwasher of this invention, as well as those of U.S. Pat. Nos. 3,180,348; 3,854,762 and patent application Ser. No. 166,082 filed July 3, 1980, now U.S. Pat. No. 4,301,822, all assigned to the assignee hereof, there is described a dishwasher having an upper rack on which is mounted a rotatable spray arm that is rotated by the reaction forces of spaced nozzles which also serve to spray washing and rinsing liquid over dishes held in the upper rack.
The rotatable spray arm is provided with liquid by an upwardly projected jet of liquid that enters a receiver and then flows into and through the spray arm thereby providing the force necessary to project the liquid through the nozzles.
As can be seen from this brief description, a most important element of such a dishwasher is the spray arm, as it is necessary not only that the arm provide nozzles for spraying the liquid over the dishes, but also that it be rotatable by the liquid pressure, that it distribute the liquid evenly over the dishes and that the liquid be distributed substantially uniformly at all radial distances from the axis of rotation of the spray arm.
The rotary spray means of this invention accomplishes these desirable and necessary functions.
The most pertinent patents of which applicants are aware are U.S. Pat. Nos. 2,359,690; 1,780,168 and 3,288,372.
Of these, U.S. Pat. No. 2,359,690 discloses a quenching nozzle having a tube with progressively contracting flow areas in combination with grooves 14 to provide a substantially uniform flow from each of the spray nozzles shown.
U.S. Pat. No. 1,780,168 discloses a fire extinguishing foam nozzle having adjustable outlets.
U.S. Pat. No. 3,288,372 discloses a sheet metal spray arm having openings formed at the apex of the dihedral angle over the top portion of a spray arm to provide a sheet-like jet of water generally aligned with the apex of the dihedral angle.
The invention as claimed herein differs from each of the structures shown in this most pertinent prior art.